Power transmission



N v. 21, 1944. H. c. NYE 2,363,196

roman 'rmsulssrbn Filed March 8, 1940 2 She'ets-Sheat 1 Q9 FIG. I\

, INVENTOR HUGH c NYE.

4 a W ATTORNEY I Nov. 21, 1944. S v H. NYE 2,363,196

POWER TRANSMISSION Filed March 8, 1940 2 Sheets-Sheet 2 |4- I [a g gs FIG. 2

DOWN

84- DOWN INVENTOR HUG H C. NY E ATTORNEY .of the venting type arranged has a delivery conduit 24' a V which-lead through combined relief and unloading valve to and 3a. Valve 36,

Patented Nov. 21, 1944 UNITED STATE s PATENT OFFICE rowan 'rnANsmssIoN Burn 0.

Nye, Detroit, Mich, a ssignorto Vickers Incorporated, Detroit, Mich., a corporation of I 7 Michigan Application March 8, 1940, Serial No. 322,963

8 Claims.

This invention relates to power transmissions,

particularly to those of the type comprising two or more fluid pressure energy translating devices one of which may; function as a pump and another as a fluid motor.

The invention is more particularly concerned.

with a power transmission system for-operating a plurality of fluid motors in sequence where it is 'desiredto control the movement of one motor from the movement of another motor. Many types of machine tools utilize two or more piston and cylinder or other typeof motors for actuating the slides of the machine, and it is frequently desirable to start the another slide has reached a predetermined position.

It is an objector the present invention to provide an improved power transmission system for operating a A'fllrthei object is to provide in. a system of this character improved control mechanism for this purpose including pump unloading means arranged for pilot control toget er with pilot valves pselectively determine the loaded or unloaded condition or the pump or p mps.

,. Further objects and advantages 01' the present invention will be apparent from the following description', r'eference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

- In the drawings:

' Figure -1 is adiagrammaticview of a hydraulic power transmission system incorporating a preferred form of the present invention.

m Figure 2 is a circuit diagram of the mechanism of Figure 1 together with a chart or the flow conditions through the various valvesin each stage oiacycle of operation. i v H Referring now to Figure 1, there is illustrated a prime mover, such as an electric motor II, which Pair of pumps I4 and It.

plurality of fluid motors in sequence.-

Eefch or the pumps J8 and II mayhave tank ports It, which are connected to tankby cont 50. These valves also have motor while the other is connected to a tank port. lre

ports 52, 54, 56 and 58,respectively;adapteikeach to be selectively connected to the pressure ort ports 52'and 54 connect by conduits 60 and 62', 'respectively, with the head and rod sides of a stationary piston 64, the latter carrying slidably mounted thereon a moving cylinder (iiiv carrying a pull head 68- and forming the main slide, for example, of a pull-up broach'. Suitable automatic tool coupling means are provided at the pull head for engaging a breaching tool in the manner well r understood in the art.

movement of one slide when Eibranch conduit 10 extends from, the conduit 60 to a hydrostatic flow-controlling valve 12 of well-known construction which serves to bypass fluid at a predetermined rate. to the tank through a conduit 14. The conduit 62 may have incorporated therein a back pressure valve 16, also ofwell-known construction, for the purpose of preventing jerky upward movement of the cylinder 66 while permitting free flow into the rod end of the cylinder for downward'movement; Briefly the valve comprises a spool ll spring biased down-.

wardly to cut 011 port 13 from port 15.. The upper end or the spool is smaller than the lower end,

- and both ends are exposed to pressure in port 15.

comes the spring and opens the valve when the so that thediflerential area at the bottom overpressure in port 15 exceeds the spring setting. A

check valve 11 is connected between ports 13 and A 15 to permit free flow from port 13 .to port 15 but to block flo w in the opposite direction.

Ports 56 and 58 of valve 38 connect. by conduits 18 and 80 withthe rod and head sides, re-

inder 8|; which machine; Asuitable directional-control,,, as shown, is oi the land and three-land for shifting the connectionsjbetween-the various spectively. of'a stationary piston 82. carries slidably mounted thereon a movable cylcarries a tool support 86 and may form the tool-handling cylinder of the breaching broa'ching tool'is indicated diagrammatically at The valves 36 and 38 may have slidable t ospools 94 and 96,. respectivel valve ports in the well-known manner. The spool l4 may be shiftedby meansora manually-open ablelever 98 while the spool 96 may be shifted by the admission (211111 1; of the operating chambers at either end of the valve. These chambers are connected by conduits Ill. and I II! to the ports 2 and l of a rotary, fourw way, pilot valve IN. A pressure latter connects by a conduit "16- w th the supply The latter I 88 togetherwith a work "abutment "Sand a pieceof work 92 positioned against the lower side thereof ready for broach ing anintemalhole therein.

pressure to one or the other rt P of/the conduit 26 from the pump [.6 while the tank port T is connected to tank by a conduit I08. The ro-- tary plug of the valve I04 is adapted to be shifted concurrently with the shifting of spool 94 by means of a lever and fork connection II2 to the lever 98.

The combined unloading and relief valves 28 and 30 are similar to each other and may be constructed as shown in .the patent to Harry F. Vickers, No. 2,043,453. Valves of this character are provided with a control chamber designated I2 in said patent which is in restricted communl cation with the pump supply line and, when exhausted to tank, permits the main valve .to open, thus bypassing the pump discharge to tank through the bypass conduits H4 and H6 in the present example. An integral pilot relief valve is provided as disclosed in the aforesaid patent for venting the controlchamber whenever the pressure therein rises beyond a predetermined value. In addition a connection to such control chamber. designated H8 and I20 in the present instance, is

provided.

Pilot conduits I2I and l22 extend from connections H8 and I20 to check valves I24 and I26, respectively. From the outlet of the two check valves a conduit I28 extends to a pilot-venting valve I30 adapted to open or close communication cordingly closes iorcing all of the discharge of pump I6 to pass to the pressure port 34 of valve 38. When lever I34 operates valve I30 to cut oil the vent for line I22 to thus cause valve 30 to between conduit I28 and a tank conduit I32 which connects to the conduit I08. The valve I is normally biased to open position and may be cloSed by Operation of a lever I34 forming a manual means for closing the vent conduit I28 and constituting with the lever 08 a. two-hand safety control for operation of the broaching machine.

' to the conduit I2I ahead of checkvalv -I24 and extending to a pilot-venting valve I38 similar to the valve I 30. The latter has, a discharge conduit I40 connected tothe conduit I08. Similarly, an

additional venting path is provided for the valve 30 and constitutes a conduit I42 connected to the conduit I22 ahead of the check valve I26 and extending to a pilot-venting valve I44 also similar to the valve I30. The discharge from valve I44 is carried away by a conduit I46 extendins to the conduit I08. 1 x

The valve I 38 isarranged to be closed by a cam I48 carried by the cylinder 84 and arranged to movement. Similarly the valve I44 is arranged to be closed by a cam I50 which contacts the In operation, with the motor I2 driving the pumps I4 and I6, the delivery of both pumps is bypassed to tank by the unloading valves 28 and 30, so long as the lever I34 is not manually depressed. This is the normal at-rest position of the mechanism and is illustrated in Figure 1 and in the first line of the table of Figure 2. The spool 36 of the valve 38 willphave'been shifted to its righthand position, as shown, during a previous cycle and will remain'in that position untilthe lever 98 is shifted downwardly.

If now the levers 90 and I34 are both depressed, a cycle of upward movement will be started and the initial flow conditions which occur are illustrated in the second line of Figure 2. Depressing lever I34 closes the vent path through valve I30, and since valve I44 is closed by the cam I50, there is no vent path'for the valve 30. The latter acclose, port 34 is connected to port 58 and pressure building up in line 26 will be transmitted through such ports into line 60 until valve 86 is shifted to the left by pressure through I06, P, I, and I02. However, as cylinder 84 isat its lowered position no movement of cylinder 84 occurs due to such connection. The closure of valve I30, however, could not load the pump I4 for the reason that the valve I88 is open providing a vent-path through conduits I2 I, I36, I40 and I08 to tank. Thus the pump I4 remains unloaded. Itwill be noted that thech'eck valve I24 prevents back flow of pressure 011 from the discharge side of check valve I26 to the tank through conduit I36 and valve I38.

The downward shifting of lever 88 shifted the spool 84 upwardly and shifted the rotary plug I I0 counterclockwise.

valve I04 admitted pilot .pressure from port P to port I and the righthand operating chamber of valve 38, thus shifting the spool 96 to the left.

The oil discharged from the lefthand end is permitted to return to tank through conduit I00,

ports 2 and T of valve I04 and conduit I08.

Shifting of spool 86.to theleft admitted pressure -oil from port 34 to port 56' where it flows through conduit I8 to the rod end of cylinder 84 thus causing the latter to move upwardly carrying the pilot of tool 88through the work and work abutment until it contacts with and is automatically coupled to the pulling head 68. Oil discharged from the head end of cylinder 84 returns to tank through conduit 80, ports 58 and 46,'and conduit 48.

As the cylinder 84 reaches the end of its stroke the cam I48 depresses the operating stem Of alve I38 to close the latter thus cutting oi! the only vent path for valve 28. The pump I4 accordingly becomes loaded, and pressure oil now flows through conduit, ports 32 and 52 and conduit contact the stem of valve I38 when the cylinder 4 has reached a predetermined point in its upward '60 to the head end oi cylinder 66. The latter starts upwardlypand' cam I60 rides oil! from the stem of valve I44 thus opening a ventpath for valve 30. through conduits I22 and I42, valve I44 and conduits I48 and: I08 to tank. Valve 30 accordingly open unloading the pump I6 which was momentarily pumping against full relief valve pressure due tothe stalling of cylinder 84 62, foot 'valve I6, ports 54 and 42 of valve 36, and

conduit 50 to tank.

During this stroke'the broaching tpolv 86 pulled through the work piece'82 to perform the broaching work. When the stroke is completed the operator may release the levers 88 and I34 to i reverse the connection at the valves 36, I04 and, I

later on, at valve 38. The fiow"conditionsat this time are illustrated in the fourth lin of Figure 2.

It will be noted that .the' pump I6 remains un-' loaded due to the cam I50 being out or contact The former established vconnections for pressure oil topass from port 32 aseaicc left and cylinder 84 remains up. Pump I4, however, is loaded due to the cam I48 being in con tact with valve N8; Accordingly, the cylinder 8 moves downwardly under the flow pressure oil directed to the rod end\thereof, and when this. movement is completed, the cam I 50 will contact r the valve 144 thus closing the th path for valve 30 and loading the pump I6 as shown by the last line of the table in Figure 2. Accordin ly, pressure oil will be directed first through conduit I06,

valve I04 and conduit I00 to shift valve 38 lath: right and then to the head end of cylinder 8 "causing the latter to move downwardly. As soon as it starts downwardly the cam I48 rides oil from th valve I38 thu venting the valve 28 and unloading the pump I4 'which was previously momentarily pumping against full relief valve prese sure due to the stalling of cylinder 68 at the lower end of its stroke. When the cylinder 84 has reached the end of its downward stroke, the levers 98 and I34 may be released thus bringing the ma- I chine to rest in the stop position previously described.

While the form. of embodimentof the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming-within the scope of the claim which follow.

What is claimed is as follows:

, 1. In a hydraulic power transmission system 7 having aplurality of fluid motors, a plurality of pumps and separate connections for supplying fluid from each pump to each of said motors, respectively, individual pilot-operated. means for unloading each pump, and a pilot valve controlled by movement of one motorto a predetermined position for controlling the unloading means or a pump supplying fluid to another motor.

- 2.:In .a hydraulic power transmission system .5; havinga plurality of fluid motors, a. plurality of .:pumps and separateconnections for supplying supplying fluid-to spectively, directional control valve means for selectively reversing the flow to each motor, individual pilot-operated means for unloading each pump, a pilotvalve controlled by movement of I one motor to a predetermined position for controlling theunloading meansoi a pump supplyin pump independently or said flrst pilot valve.

3. In a hydraulic power transmission system 'having a pluralityot fluid motors,,a pluralityoi' .pumps and; separate connections for supplying iluidl from each pump toeach or said motors, re-

spectively, individual valves for unloading each pump, each valve having a control chamber-in restricted communication with the pump delivery,

and a pilot valve controlled by movement of one motor to a predetermined position for venting the control chamber of .theunloading valve of a pump another motor. to unload said 4. In a hydraulic-power ton having a plurality of fluid-motors, a plurality of having a control chamber in restricted communication with the pump delivery, a pilot valve controlled by movement of one motor to a predetermined position for venting the control chamber of the unloading valve of.a pump supplying fluid to another motor to unload said pump, and a separate manually-operable pilot valve in circuit with the first pilot valve to effect unloading of the lastmentioned pump independently of said first pilot valve. 5.- In a hydraulic power transmission system having a pair of fluid motors, a pair of pumps and separate connections for supplying fluid from each pump to'each 01 said motors, respectively, individual valves for unloading each pump, each valve having a control chamber in restricted communication with the pump delivery, a pilot valve controlled by movement of each motor to a predetermined position for venting the control cham- 7 her of th unloading valve of the pump supplying fluid to the other motor to unloadsaid pump, and a single additional pilot\valve connected toboth controlflchambers to eiIect simultaneous venting thereof.

' .6. ma hydraulic power transmission system having a pair of fluid motors-a pair of pumps and 1 separate connections for supplying fluid from each pump to each of said motors, respectively,

individual valves for unloading each pump, each valve having a control chamber in restricted communication with the pump delivery, a pilot valve controlledby movement of each motor to a predetermined position for venting the control chamber of the unloading valve of the pump supplying fluid to the other motor to unload said pump, and

a single additional pilot valve connected by check valves .to both control chambers to eilfect simulf' taneous venting thereof.

7. In a hydraulic power transmission system having a pair or fluid motors, a pair of pumps and separate connections for supplying fluid from each pump to each of said motors, respectively,

individual valves for unloading each ump, each valve having a control chamber in restricted conn munication with the pump delivery, a pair of separate pilot valves each-connected to vent the control chamber of a respective unloading valve,

and a separate pilot valve connected to both control chambers to simultaneously unload both pumps. i 7

having a plurality of fluid motors, a plurality oi pumps and separate connections for supp in fluid from each pump to each of said motors. re-

' spectively, individual valves for unloading each pumps and separate connections ton-supplying pump, each valve having a control chamber in restricted communication with thepump delivery.

and pilot valve;means having connections to vent the control chambers oi! each unloading valve separately or jointly for selectively unloading any one. of the pumps or more than one pump, re-

spectively.

H, HUGH C. NYE.

v 8. In a hydraulic power transmission system 

